Whats wrong - help pls

Question

I have a main method which accepts/expects the username and password as its arguments.
The problem when i run this code is
instead of displaying the error message
System.err.println("Username not present");
the program gives the following runtime error
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at Banni11sear.main(Compiled Code)
I know i can catch this using but i want to display my own error message.I don't know why the following code is giving runtime error instead of displaying the "username not present"
any help is appreciated
-sagarika
* This is the main method.
* @par String[] args. The main method expects the
* username and password as arguments.
* The format would be
* java <filename> -u username -p password
public static void main(String[] args) {
if (args[1] == null) {
System.err.println("Username not present");
System.exit(1);
if(args[3] == null) {
System.err.println("Password not given");
System.exit(1);
Sample sample = new Sample(args[1], args[3]);
sample.close();
}

Answer 1

and i posted a reply and fixed code in another one...
http://forum.java.sun.com/thread.jsp?thread=314204&forum=48&message=1262390
please do not cross-post!